How does oxidized cholesterol enter the bloodstream?

Answer 1

It was very refreshing to see your question. I have never once heard an MD or any other medical professional discuss the role of oxidized cholesterol, unless it was in a research paper, despite the momentous role it plays in atherosclerosis. Only oxidized LDL cholesterol initiates the chain of events that lead to the formation of arterial plaques and ultimately to arterial stenosis. This is why one should never eat certain foods and why almost everyone should supplement their diet with vitamin C and lipoic acid, which is usually called "Alpha Lipoic Acid" on a supplement label.

Depending mostly on ones diet, including the antioxidants he consumes, oxidized cholesterol may enter the bloodstream by ingestion. In most cases, however; cholesterol in the form of LDL is oxidized after it has penetrated the endothelium lining of the artery wall.

There are many oxidized forms of cholesterol. This contributor does not know if any of those forms are capable of entering the bloodstream after being ingested. Everything that is absorbed following ingestion goes to the liver first via the hepatic portal vein before entering the entire bloodstream. If oxidized cholesterol is absorbed by the gut, I do not know what the liver does with it. Perhaps they are stored as part of bile and never make it into the bloodstream proper. But given that just the hydrophobic core of a typical LDL cholesterol particle contains about 1,500 cholesterol molecules, I would guess that the liver includes some fraction of oxidized cholesterol molecules in LDL cholesterol.

Until the fate of ingested oxidized cholesterol is known, I would consider powdered eggs one of the worst foods one can eat. During the process of turning true eggs into powdered ones, at least some of the cholesterol in the egg yolks is oxidized. The same thing probably occurs in making whole condensed milk. A significant fraction of the non-trivial amount of cholesterol in cheese becomes oxidized as it ages. Mild cheeses, and especially fresh mozzarella cheeses including queso fresco, have the least amount of damaged cholesterol. In summary, any [animal] product that contains a lot of cholesterol should not be burned or over heated. This means that one should limit the amount of grilled meat and seafood cooked over an open flame such that it becomes charred. Steam shrimp, lobster, crab, oyster and all shellfish, all of which are very high in cholesterol, rather than scorching them over a flame.

Can powerful antioxidants like lipoic acid chemically reduce ingested oxidized cholesterol back to cholesterol? This contributor doesn't know. The simplest oxidized cholesterol is 7-hydroxycholesterol; it is possible that this least oxidized form may be reduced back to the parent compound by reductase enzymes, ascorbic acid, lipoic acid, vitamin E and other natural tocopherols, especially ∂-tocopherol which is a more powerful antioxidant than vitamin E.

In my opinion, the best strategy to limit arterial plaques is to 1) Inherit good genes and do not get any older than 40. 2) Eliminate or strictly limit the ingestion of oxidized cholesterol, at least until it is proven that none of the oxidized forms of cholesterol end up in the bloodstream. 3) Eat a diet that minimizes the liver's production of LDL and VLDL (Very Low Density Lipoprotein) cholesterol and maximizes the production of HDL cholesterol. 4) Ensure that there are always adequate concentrations of the two strongest, but safe and natural, antioxidants and radical scavengers in the bloodstream; those being L-ascorbic acid, the natural isomer of vitamin C, and lipoic acid. 4a) Take 500 mg of vitamin C and 100 mg of lipoic acid every morning, even on an empty stomach. Smokers or persons who work near automobile exhaust, smoke, or vapors or aerosols of oxidizing agents such as hydrogen peroxide or sodium or potassium nitrate dust should take 1000 mg of vitamin C and 200 mg of lipoic acid. The same holds true for anyone who performs vigorous exercise for more than 3 hours per week. Strenuous exercise is a very oxidative process that produces many radicals. In my opinion, exercising vigorously for more than approximately three hours per week is detrimental to that person's heart health. One warning! Anyone on medication for Diabetes should not take lipoic acid until he has obtained the okay from his doctor. 4b) Take 500 mg of vitamin C and 100 mg of lipoic acid every evening. Take more if the conditions in 4a apply.

Lipoic acid is produced naturally by most cells in the body, but that does not necessarily mean that its concentration in the blood is sufficiently high to prevent cholesterol oxidation. Lipoic acid will reduce oxidized vitamin C back to vitamin C, and it has the same effect on vitamin E. It is capable of chemically reducing oxidized vitamins C and E because it is both water- and fat-soluble. The goal of eating a diet high in colored vegetables and supplementing one's diet with vitamin C and lipoic acid is to prevent LDL cholesterol from being oxidized before or after it has penetrated the arterial wall. Diets low in cholesterol are of no or little use in reducing one's cholesterol levels since the vast majority of serum cholesterol is synthesized in that person's liver.

The reason LDL cholesterol is particularly dangerous is because it penetrates the arterial wall. If the LDL cholesterol in the arterial wall is oxidized, proteins called cytokines are released. Cytokines are part of the immune system and they trigger an immune response by causing the endothelium cells (the single layer of cells that line the arterial walls) to attract monocyte white blood cells. These cells penetrate the arterial wall, become macrophages, and begin to "eat" the oxidized LDL cholesterol particles as if they were bacteria or viruses, which is what macrophages normally do. Some of the macrophages rupture and die, spilling their contents into the intercellular spaces. At this point, an arterial plaque has been created. The lost contents of the ruptured macrophages attract even more of them causing the plaque to thicken. Eventually, the plaque becomes so viscous that macrophages can no longer penetrate it, however macrophages not only consume antigens, they can release lysing enzymes that dissolve part of the arterial wall underneath the plaque, thereby destroying its structure. In some places, the membrane separating the plaque from the inside of the artery may become thin enough for it to rupture when the heart beats (at maximum blood pressure). The exposed plaque material precipitates a clotting response so that a clot is formed over the plaque. Repeated cycles of plaque rupture and subsequent clot formation eventually leads to narrowing of the artery at the location of the plaque, and the artery can become completely blocked. If that artery happens to be a coronary artery, a heart attack will ensue, although it is not necessary to have a completely blocked artery to cause a heart attack. This is exactly what happened to my father almost two years ago. He is fine now after four stints were placed where there were four severely blocked coronary arteries.

Arterial plaque may cause a heart attack or a stroke in a different manner. A clot isn't only formed over a ruptured plaque, but also on or around any plaque material that is carried away by the blood flow, and it will eventually block a blood vessel. If the clot is small enough, it will only block capillaries and no major damage is done. However, larger clots will block larger blood vessels, and if a sufficiently large vessel is blocked in the brain, the result will be a stroke, or a cerebral thrombosis. The blockage could occur in an coronary artery resulting in a coronary thrombosis.

Answer 2

through your urine. It's called lipiduria and is quite common in people who are actively dieting.

Answer 3

it is carried throughout the body in the bloodstream

Answer 4

HDL